This invention relates to electrostatographic reproduction machines, and more particularly to an economical and capacity-extendible all-in-one process cartridge for easy adaptive use in a family of compact electrostatographic reproduction machines having different volume capacities and consumable life cycles. Specifically this invention relates to such a cartridge including a printing cartridge with a positive gear mounting arrangement.
Cross reference is made to the following application filed concurrently herewith: U.S. patent application Ser. No. 09/049557, entitled "Rigid Interference Gear Mount for Enhanced Motion Quality" by Ajay Kumar et al.
Generally, the process of electrostatographic reproduction, as practiced in electrostatographic reproduction machines, includes charging a photoconductive member to a substantially uniform potential so as to sensitize the surface thereof. A charged portion of the photoconductive surface is exposed at an exposure station to a light image of an original document to be reproduced. Typically, an original document to be reproduced is placed in registration, either manually or by means of an automatic document handler, on a platen for such exposure.
Exposing an image of an original document as such at the exposure station, records an electrostatic latent image of the original image onto the photoconductive member. The recorded latent image is subsequently developed using a development apparatus by bringing a charged dry or liquid developer material into contact with the latent image. Two component and single component developer materials are commonly used. A typical two-component dry developer material has magnetic carrier granules with fusible toner particles adhering triobelectrically thereto. A single component dry developer material typically comprising toner particles only can also be used. The toner image formed by such development is subsequently transferred at a transfer station onto a copy sheet fed to such transfer station, and on which the toner particles image is then heated and permanently fused so as to form a "hardcopy" of the original image.
It is well known to provide a number of the elements and components, of an electrostatographic reproduction machine, in the form of a customer or user replaceable unit (CRU). Typically such units are each formed as a cartridge that can be inserted or removed from the machine frame by a customer or user. Reproduction machines such as copiers and printers ordinarily include consumable materials such as toner, volume limiting components such as a waste toner container, and life cycle limiting components such as a photoreceptor and a cleaning device. Because these elements of the copying machine or printer must be replaced frequently, they are more likely to be incorporated into a replaceable cartridge as above.
There are therefore various types and sizes of cartridges, varying from single machine element cartridges such as a toner cartridge, to all-in-one electrostatographic toner image forming and transfer process cartridges. The design, particularly of an all-in-one cartridge can be very costly and complicated by a need to optimize the life cycles of different elements, as well as to integrate all the included elements, while not undermining the image quality. This is particularly true for all-in-one process cartridges to be used in a family of compact electrostatographic reproduction machines having different volume capacities and elements having different life cycles.
There is therefore a need for a quality image producing, economical and capacity-extendible all-in-one process cartridge that is easily adapted for use in various machines in a family of compact electrostatographic reproduction machines having different volume capacities and elements with different life cycles.
Printing or process cartridges include a number of components which rotate. For example, such components include a photoconductive drum, a developer roll, augers, and agitators which are used to move the marking particles about the toner cartridge. These rotating elements are rotated by a motor or motors connected thereto. For simplicity and to reduce cost, at least some of the rotating components are mechanically interconnected by means of a mechanical drive train. The slow rotating speeds of the shafts within a printing cartridge often are accommodated by a transmission consisting of several meshing gears.
The use of a number of gears meshing together to rotate the elements of the printing cartridge require that a large, rigid housing be used to accommodate the gear forces utilized in the printing machine. The gears are typically positioned at ends of the shafts which the gears are designed to rotate.
The relative rotational speeds of the paddles, augers, photoreceptors and developer rolls frequently need to be adjusted to optimize the performance of the machine and to improve quality. Often, many gears may need to be changed to speed up or slow down only one particular rotating mechanism.
To promote recycleability and to keep manufacturing and material costs to a minimum, the gears in a process cartridge typically are made of plastic. These gears wear quickly, have low precision, and as such may be responsible for motion quality problems including deletion and banding errors.
The gears, particularly if they are helical gears, require axial restraints and, in the case of helical gears, require thrust faces to accommodate the thrust from the gear forces.
The gears are often mounted or assembled onto shafts. The shafts may be in the form of paddles, augers, photoreceptors or developer rolls. The mounting of the gears onto the shaft is typically accomplished by a cylindrical journal on the ends of the shafts to which the cylindrical bore of the gear is matingly fitted. To provide for enhanced torque carrying capacity, the shaft may include a flat which is matingly fitted with a flat on the bore of the gear.
A typical prior art gear is shown as gear 1 in FIG. 9. The gear 1 includes teeth 2 located on the periphery thereof. Centrally located within the gear 1 is a bore 3. The bore 3 is matingly fitted to shaft 4. The bore 3 includes a flat 5 which cooperates with flat 6 of the shaft 4. Manufacturing tolerances for the shaft 4 and the gear 1 require the shaft 4 and the bore 3 to have clearance therebetween. Thus, as the gear 1 and the shaft 4 have relative motion therebetween the shaft 4 may move from first position 7 to second position 8. The relative motion between the gear 1 and the shaft 4 contribute to image quality problems as previously mentioned. In particular, the relative motion between the gear and the shaft causes deletion and banding errors. This can occur because the sheet may advance more quickly than the photoconductor or conversely the photoconductor may advance more quickly than the sheet.
The following disclosures may be relevant to various aspects of the present invention: